HDQRS. SECOND CORPS, ARMY OF THE MISSISSIPPI,
On board Forest Queen, January 5, 1863.

SIR: Communication with General Grant seems cut off; at all events so difficult that much time will be consumed in my transmitting thought him an official account of our movements on the river that I have concluded to send you direct-

First. A copy of my official report.

Second. A map of the ground and water before Vicksburg.

Third. My official instructions to commanders of divisions.

Fourths. Copy of my orders for the assault and battle.

I reached Vicksburg at the time appointed, landed, assaulted, and failed. Re-embarked my command unopposed and turned it over to my successor, General McClernand. At first I proposed to remain near Vicksburg, to await the approach of General Grant of General Banks to co-operate, but as General McClernand had brought intelligence, the first that had reached me, that General Grant had fallen back of the Tallahatchie, and as we could hear not a word of General Banks below, instead of remaining idle I proposed we should move our entire force in concert with the gunboats to the Arkansas, which is now in boating condition, and reduce the Post of Arkansas, where 7,000 of the enemy are entrenched and threaten this river. One boat, the Blue Wing, towing coal-barges for the navy and carrying dispatches, has been captured by the enemy; and with that enemy on our rear and flank our communications would at all times be endangered. General McClernand agreed and Admiral Porter also cheerfully assented, and we are at this moment en route for the Post of Arkansas, 50 miles up the Arkansas River.

Pardon me for a few general remarks on the topography of Vicksburg, which now stops our progress down the main river. The high ridge to land lying between the Big Black and Yazoo is known as the Walnut Hills. Their summits are about 200 feet above average water of the river. The Mississippi impinges against these hills and makes a steep bluff at the city for about 2 miles above and several below. The Yazoo, coming from the northeast, clings to this range of hills on its east, but all ground to its west is Mississippi alluvion. The present Yazoo leaves the hills at a point about 23 miles above its present mouth, at a place known as Haines' Bluff, the lower end of which is now properly Drumgould's Bluff. The present mouth of Yazoo is 10 miles above Vicksburg, so that an irregular triangle of alluvion lies between the Yazoo and Walnut Hills. The distance by land from Vicksburg to Grumgould's is 14 miles. The Yazoo in old times evidently clung to these hills, and his left old channels or bayous of deep, stagnant water and mud, and the whole triangle is cut up in every imaginable from by these bayous. The map I send will give you the best idea. The present river and the old bayous are all leaved against high waters, and the lands are as fertile as any on earth. These levees vary in height from 4 to 18 feet; their shape the same as a military parapet. Interior slope 45 degrees; superior slope from, 12 to 15 feet, for a roadway; exterior slope about 1 to 4. These levees enter largely into the enemy's system of defense. Where these levees are continuous, as along the Mississippi River and along the bayou from Vicksburg to Haines; Bluff, a separate roadway is made behind the levee. It was along such a road that our enemy moved his masses of infantry and artillery perfectly under cover and yet ready to meet us whenever we succeeded in reaching it. The face of the hills between Vicksburg and